MEMS sensors typically use a deformable membrane that deflects under applied pressure. For capacitive pressure sensors, an electrode on the membrane deflects toward a fixed electrode under increasing pressure leading to a change in the capacitance between the two electrodes. This capacitance is then measured to determine the pressure applied to the deformable membrane. Similarly, capacitive microphones respond to acoustic vibrations that cause a change in capacitance.
While the basic MEMS sensor described above is operable, the basic device structure does not provide sufficient accuracy needs in many applications. Accordingly, more complex structures have been investigated in hopes of providing the increased accuracy needs of various applications. While there has been some success in increasing the accuracy of MEMS sensors, significant challenges are encountered. Some of the challenges that are commonly encountered include: temperature sensitivity of the sensor; differences in temperature sensitivity of the variable capacitance (the membrane) and a reference capacitance (unaffected by pressure); the need for electrostatic actuation or additional measurement; and the limited measureable pressure range set by the geometry and material properties of the MEMS sensor structure.
In view of the foregoing, it would be beneficial to provide a MEMS pressure sensor which accounts for variations in temperature. It would be further beneficial if such a pressure sensor did not require significant additional space. A MEMS pressure sensor which accounts for variations in temperature which can be fabricated with known fabrication technology would be further beneficial. A pressure sensor which additionally provides an increased operational range would also be beneficial.